Journal of Pure and Applied MicrobiologyVol. 8 No. May 2014 Special Edition

Effects of Grape Polyphenols on the Quality and Antioxidant Activity of Yoghurt

Yu-e Ye1, Lan Li1, Ming Ye*, Min Zhang, Lian-yan Jing and Liu Yang

College of Biotechnology and Food Engineering, Hefei University of Technology, Hefei - 230009, Anhui, China.

Received on 21 January 2014 and accepted on 12 March 2014

 

ABSTRACT

Grape polyphenols yoghurt (GPY) was prepared from the mixture of grape polyphenols (GP) and the reconstituted milk. The final product was subjected to the analysis of lactic acid bacteria number, physicochemical property. It was found that the counts of Lactobacillus delbrueckii subsp. bulgaricus declined gradually whereas the counts of Streptococcus thermophilus increased in the range of 0.1-0.4 g/L (GP), meanwhile the reducing power, DPPH? scavenging activity and Fe2+ chelating ability of the GPY increased significantly. These results indicated that GP can significantly enhance the antioxidant activity of yoghurt. The pH, viscosity and susceptibility to syneresis increased gradually in the range of 0.1-0.7 g/L (GP). During the 0-18th days, the total counts of lactic acid bacteria and the pH of the GPY had significantly slower decrease than that of the control yoghurt (CY). The above results indicated that addition of GP can significantly enhance the antioxidant activity of yoghurt, and GP has a protective effects on the survival of the lactic acid bacteria.

Keywords : Grape polyphenols yogurt (GPY), Counts of lactic acid bacteria, Quality, Antioxidant activity, Preservation period.